Louvred structures such as louvred doors and/or window shutters, etc. often include moveable louvres which pivot through an angle of slightly less than 180.degree.. In most moveable louvre structures, the louvres are opened and closed in unison with one another by a control bar attached to the edges of the louvres. The control bar moves in an up and down direction to open and close the louvres. This control bar adds weight to one side of and imbalances the louvres. When the louvres are closed and the control bar is down as far as it will go, this does not present a problem. However, when the louvres are opened, the weight of the control bar provides a downward bias wanting to close the louvres.
Traditionally, the means for holding a set position of a moveable louvre is to provide strong frictional resistance between the louvre and its supporting frame. Typically, this is done by effectively clamping the frame tightly against the outside edges of the louvre. In certain constructions, and in particular, in vinyl constructions, it is neither desirable nor feasible to provide sufficient frictional resistance between the louver and the frame to hold a desired set louver position.